In recent years, in electrical systems, the use of capacitor units for phase correction has become more and more common place. Capacitors are usually mounted in banks, and have any convenient, or desired kvar. ratings. It is very desirable to have a current-limiting fuse in series with each capacitor to prevent case rupture in the event of breakdown, and to prevent damage to the entire capacitor bank. Preferably, the fuse should be capable of disconnecting itself from the circuit, thereby eliminating tracking, which can cause oscilatory current which can damage other capacitors in the bank.
In one well-known type of capacitor-bank construction, an indicating fuse is mounted on the aluminum bus above each capacitor unit. Connection to the capacitor units is made by a flexible pigtail. The pigtail is passed through a coil-spring fuse-element ejector and indicator mounted up on the capacitor-unit terminal. The spring is held in a curved position when the fuse is intact. When the fuse blows, the spring retracts to a horizontal position, pulling the pigtail, or fuse link from the fuseholder. Normally, the strain link of prior art fuses, that is, the link which resists the force of the coil spring is in tension, requiring that the link be firmly anchored at one end to a conductor rod, and be anchored at the other end to the pigtail of the fuse. An improved construction of such type is set forth in U.S. Pat. No. 3,259,719, issued July 5, 1966, to Robert T. Innis and George A. Rusnak, and assigned to the assignee of the instant application.
U.S. Pat. No. 3,467,934, issued Sept. 16, 1969 to Robert T. Innis and George E. Mercier, teaches a two-part indicating fuse adaptable for capacitor-unit protection, and including a flexible fuse casing. It is contempated in this patent that when fuse operation occurs, there will result a breakaway action between the two fuse casing sections of the device to thereby permit a visible indication of fuse operation.